California's Darrell Issa, the wealthiest member of Congress, is keeping his House seat, the Associated Press reports.
The eight-term Republican and chief antagonist of President Barack Obama survived a fierce fight with political neophyte Democrat Doug Applegate in his coastal district north of San Diego.
Unofficial returns Monday show Issa holding a 2,300-vote edge, with only a small number of votes left to tally. Vote-counting extended for weeks after the election as officials tallied late-arriving mail ballots and those filled out at polling places.
Donald Trump's presence at the top of the ticket in Democratic-tilting California and changing demographics in the district made the contest much closer than expected.
Issa is the former chairman of the House Oversight and Government Reform Committee.
His fortune from a car-alarm manufacturing business has been estimated at more than $250 million.